Refer to the exhibit. All five nginx pods are scheduled on the same node (default-pool-1). What is the most likely reason?
Correct: If nodes have taints, pods without matching tolerations will not be scheduled on them, causing all pods to land on the node without taints.
Why this answer
Taints on nodes prevent pods from being scheduled unless the pods have corresponding tolerations. If the other nodes have taints that the nginx pods do not tolerate, the scheduler will only place them on nodes without those taints, which in this case is default-pool-1. This is a common scenario when nodes are dedicated to specific workloads or have special hardware.
Exam trap
This question tests the distinction between taints/tolerations and nodeSelector/affinity in Kubernetes on Google Cloud. Candidates often overlook that taints can silently exclude pods from all but one node, and assume only nodeSelector restricts pod placement.
How to eliminate wrong answers
Option A is wrong because the node auto-scaler adds nodes when pods are unschedulable due to resource constraints, but here all pods are scheduled on one node, indicating the scheduler deliberately chose that node, not that other nodes are missing. Option B is wrong because if a nodeSelector matched only default-pool-1, the pods would be scheduled exclusively there, but the question asks for the 'most likely reason' and taints are a more common cause for pods being forced onto a single node when other nodes exist. Option D is wrong because if resource requests were too high, the scheduler would leave pods pending or spread them across nodes that can fit them, not pack them all onto one node; packing suggests the other nodes are intentionally excluded.